Existing technologies that automatically place outbound telephone calls, such as predictive dialing systems, are used by many companies to greatly improve the efficiency of their agents. Such systems are used by telemarketing companies, market research companies, and are heavily used by companies making collection calls. Such systems rely on hardware and/or software to determine the result of an outbound placed call. It is desirable that the system know the difference between a human answer, an answering machine, a busy signal, and a disconnected or not in service number recording in order to send only human answered calls to agents. The primary method for detecting that a call is being placed to a disconnected or not in service number is monitoring the line for the distinctive “tones” received or detected prior to the disconnected or not in service recordings. The frequency of these tones can be detected and the call can then be classified as disconnected or not in service.
Recently devices have been marketed to the general public, which are placed on their telephone line that falsely transmit the “tones” normally transmitted by the telephone network to signify a disconnected or not in service number. One such device is known as the Telezapper®, sold commercially by Privacy Technologies, Inc, a wholly owned subsidiary of Royal Appliance Manufacturing Co., a corporation located in the state of Ohio. While such devices have been marketed with the intent of stopping unwanted telemarketing calls, their use has caused problems for anyone placing calls to such telephone lines for legitimate business purposes such as to collect a debt owed by a person at the called number, or calls from companies with which the person has an existing business relationship, in which cases the called person may indeed wish to receive the call. Thus, there is an unsatisfied need for properly distinguishing between false tones transmitted by such devices and the valid tones sent by the telephone network.